1. Field of the Invention
The present invention relates to a container having a sealed flap closing one end of the container with the seal adjacent one end of the flap of a reduced bonding strength to facilitate opening the bag, while maintaining a seal prior to opening. More particularly, the present invention relates to a bag having a flap hingedly coupled at one end of the bag and sealed to one of the bag panels with a portion of the seal adjacent one bag corner having a reduced adhesive bonding strength to facilitate opening of the bag at the flap corner.
Additionally, the invention relates to a laminate comprising a localized coating of an abhesive composition on a cellulosic substrate wherein the abhesive layer is superposed over an adhesive layer.
2. Description of the Prior Art
Containers or bags formed of heavy weight, multiple ply paper are conventionally employed for containing, storing and shipping flowable, fine powdery materials and small sized granular products, such as starch, food products, chemicals, cement and the like. The flowable nature of these products permits the bags to be filled by inserting a filler spout of a dispensing machine into an opening of the bag and delivering the product from a source through the spout into the bag. The bag construction and filling apparatus for filling bags in this manner are disclosed in U.S. Pat. No. 4,316,574 to Lepisto, which patent is hereby incorporated by reference.
One problem which has plagued bags of this type is the provision of a simple and neat way to open the bags without using tools. Often heavy weight bags have no provision to facilitate opening and require the use of a sharp instrument to cut an opening in the bag. Such opening procedure is inconvenient and dangerous. Additionally, opening the bag using a sharp instrument often results in tearing of the bag preventing proper resealing for storing any remaining bag contents and preventing controlled dispensing of the contents.
Hand opening of heavyweight bags sealed with hot melt adhesive is extremely difficult due to the strength of the bag material and the seal. Force applied to the closing flap will tear the bag since the bond between the adhesive and paper is stronger than the paper itself. Thus, hand opening of such bags is difficult, forms a poor dispensing spout, causes spilling of the contents, and prevents resealing of the bag.
Special mechanisms for opening bags have involved the use of strings, e.g., U.S. Pat. No. 2,203,924 to Pletscher and U.S. Pat. No. 2,151,523 to Orr, the inclusion of a glued tab, e.g., U.S. Pat. No. 3,081,930 to Owens and the use of tape, e.g., U.S. patent application Ser. No. 243,829, filed Mar. 16, 1981, entitled "Easy Open Valve Bag".
The previously tried closure opening mechanisms have suffered from numerous deficiencies, including a high failure rate, difficult and expensive manufacturing, adverse effects on the sealing of the bag and difficult operation. The string often fails by becoming loose from the bag without tearing the bag material and is difficult and expensive to install due to the precise gluing necessary. The thick material of the bag often makes the tab and tape mechanisms difficult to open. Additionally, such opening mechanisms provide a relatively large opening making controlled dispensing of the contents and resealing of the bag difficult.
Thus, previous systems for opening heavyweight bags for powder and granular substances have not been effective since they are difficult and expensive to manufacture, have a high failure rate, are difficult to operate and do not form a neat pouring spout for accurately dispensing the bag contents. Additionally, these systems make it extremely difficult or impossible to reseal the bag to properly store any unused contents in the bag.